Shock-wave initiation of detonations in propane / air mixtures

Functioning of propulsion devices based on supersonic combustion modes is usually accompanied by the formation and propagation of shock waves, which produce the necessary level of thermal excitation of the mixture to maintain high rate of energy release in the system. In some cases, apparatus design can be considered as a single self-consistent device in which interactions of shock waves with confinement walls and inner flow structure sustain the propagation of fast deflagrations and detonations along a certain trajectory. Under such approach, the confinement geometry can facilitate substantially the mixture re-ignition inside combustion chamber due to the effects of shock focusing [1-5]. This work addresses to systematic experimental and numerical investigations of auto-ignition phenomena at shock wave interaction with reflecting ducts of different geometry in propane/air mixtures, which are used as a model fuel for many studies of detonations. Under this studies the self-ignition and initiation domains in stoichiometric propane-air mixtures have been investigated under shock wave focusing in 1 hemi-spherical and hemi-cylindrical reflectors with radii R= 38 mm; 2 wedge and cone reflectors with apex angles of 90 ; 3 parabolic and paraboloidal reflectors.